[Technical Field]
[0001] The present invention relates to a new iron-copper (Fe-Cu) alloy containing iron
(Fe) as a main component and an appropriate amount of copper (Cu), which has high
thermal conductivity and mechanical properties along with, for example, an electromagnetic-wave
shielding property and a soft magnetic property.
[Background Art]
[0002] Metal-related industries are replacing existing steel materials with lightweight
material, such as aluminum (Al) alloys. The aluminum alloys are being widely employed
for a variety of uses in many industrial fields owing to their excellent properties,
including, for example, lightness in weight, thermal conductivity, corrosion resistance
and ductility. The aluminum alloy having high thermal conductivity enables rapid cooling,
thereby minimizing distortion or warpage of a molded article. Hence, the aluminum
alloy can be useful as a molding material for injection molding or die casting.
[0003] For example, techniques of aluminum alloys for die casing have been proposed in Korean
Patent Publication No.
10-2015-0046014 and Korean Patent Registration No.10-1606525. The aluminum alloy contains aluminum
(Al) as a main component and small amounts of silicon (Si), iron (Fe), manganese (Mn)
and magnesium (Mg), and aluminum-silicon-magnesium (Al-Si-Mg) type alloys are widely
used as molding materials for die casting.
[0004] However, the aluminum alloy has poor mechanical properties in view of strength or
abrasion resistance. Accordingly, beryllium-copper (Be-Cu) alloys having high thermal
conductivity and corrosion resistance and good mechanical properties, such as strength
and abrasion resistance, are growing popular as molding materials. Techniques concerning
the Be-Cu alloys are disclosed in Japanese Patent Publication No.
JP 2003-003246, Korean Patent Publication Nos.
10-2012-0048287 and
10-2015-0053814, and so on.
[0005] The Be-Cu alloy is a practical alloy having high strength and high thermal conductivity
and is advantageously used as molding materials for die casting. The Be-Cu alloy is
generally obtained by repeatedly performing melt-casting beryllium (Be) and copper
(Cu), performing a hot or cold plasticizing work, and performing annealing treatment,
and cobalt (Co) is added to improve mechanical properties of the Be-Cu alloy. However,
it is quite difficult to continuously cast the Be-Cu alloy and material costs of beryllium
(Be) and copper (Cu) are very high, making a Be-Cu alloy manufacturing process uneconomic.
Hence, the Be-Cu alloy is restrictively used in the manufacture of only premium products
due to its high cost, thereby preventing its widespread application for general uses.
[Technical Problems to be Solved]
[0006] The present invention provides an iron-copper (Fe-Cu) alloy having improved properties
with a new iron-based alloy composition, by which existing beryllium-copper (Be-Cu)
alloys can be replaced, a method of manufacturing the same, and uses thereof.
[0007] Specifically, the present invention provides an iron-copper (Fe-Cu) alloy containing
an appropriate amount of copper (Cu) in an iron (Fe) base, which has high thermal
conductivity and mechanical properties along with, for example, an electromagnetic-wave
shielding property and a soft magnetic property, a method of manufacturing the same,
and uses thereof. In addition, the present invention provides materials containing
the iron-copper alloy as uses of the iron-copper alloy.
[Technical Solutions]
[0008] To achieve the above and other objects, the present invention provides an iron-copper
(Fe-Cu) alloy including 55 to 95 atomic % of iron, and 5 to 45 atomic % of copper.
[0009] In addition, the present invention provides an iron-copper (Fe-Cu) alloy including
80.5 to 95 atomic % of iron, and 5 to 19.5 atomic % of copper, wherein the iron-copper
alloy has the following properties (a) to (c):
- (a) thermal conductivity of greater than or equal to 70 W/m · K;
- (b) tensile strength of greater than or equal to 300 N/mm2; and
- (c) hardness of greater than or equal to 100 HB.
[0010] In an exemplary embodiment, the iron-copper (Fe-Cu) alloy according to the present
invention may have a spherical particle shape and may have a particle size of 0.1
µm to 150 µm.
[0011] In addition, the present invention provides a method of manufacturing an iron-copper
(Fe-Cu) alloy, the method including a first step of preparing a melting furnace, a
second step of adding iron and copper to the melting furnace and performing dissolution
and molten metal formation so as to contain 55 to 95 atomic % of iron and 5 to 45
atomic % of copper based on the weight of the iron-copper alloy, a third step of stabilizing
the molten metal, and a fourth step of pouring the stabilized molten metal into a
casting mold and performing casting.
[0012] In an exemplary embodiment, the method may further include a fifth step of obtaining
iron-copper alloy particles by remelting a casting obtained in the fourth step and
then injecting the remelted casting.
[0013] In a preferred embodiment, the first step includes performing surface treatment for
forming a porous impurity absorption layer on an inner surface of the melting furnace.
Here, the impurity absorbent preferably contains zirconium silicate.
[Advantageous Effects]
[0014] As described above, according to the present invention, a new iron-based alloy which
can replace existing beryllium-copper (Be-Cu) alloys is provided. The present invention
can provide the iron-copper alloy that is an amorphous, complete molten alloy containing
iron (Fe) as a main component and an appropriate amount of copper (Cu), which has
high manufacturability and economic efficiency while having high thermal conductivity
and excellent properties. In addition, the present invention can provide the iron-copper
alloy having high thermal conductivity and mechanical properties along with, for example,
an electromagnetic-wave shielding property and a soft magnetic property, which can
be widely used for not only molding materials but also electronic parts and machine
parts.
[Brief Description of Drawings]
[0015]
FIG. 1 shows a B-H curve (magnetization curve) of an iron-copper alloy prepared in
Example of the present invention.
FIG. 2 shows scanning electron micrograph (SEM) photographs of iron-copper alloy particles
prepared in Example 4 of the present invention according to magnification scales.
FIG. 3 shows an EDS analysis result of iron-copper alloy particles prepared in Example
4 of the present invention.
FIG. 4 shows an EDS analysis result of iron-copper alloy particles prepared in Example
5 of the present invention.
FIG. 5 shows an EDS analysis result of iron-copper alloy particles prepared in Example
6 of the present invention.
FIG. 6 shows an SEM photograph of a particle sample prepared in Comparative Example.
[Best Mode for Carrying Out the Invention]
[0016] As used herein, the term "and/or" includes any and all combinations of one or more
of the associated listed items. In addition, as used herein, the term "at least one"
is intended to include plural forms, i.e. one and more than two", unless the context
clearly indicates otherwise.
[0017] In an embodiment, the present invention provides an iron-copper (Fe-Cu) alloy that
is an iron based alloy containing iron (Fe) as a main component, which has a new alloy
composition. According to another embodiment of the present invention, there is provided
a method of manufacturing the iron-copper alloy.
[0018] In addition, according to a further embodiment of the present invention, there is
provided a use of the iron-copper alloy that is a material containing at least the
iron-copper alloy. For example, the material can be selected from a molding material
and a material for a 3D printer.
[0019] The iron-copper alloy according to the present invention containing iron (Fe) and
copper (Cu) is an iron based alloy having the iron (Fe) content higher than the copper
(Cu) content, the iron-copper alloy comprising 55 to 95 atomic percentage (%) of iron
(Fe) and 5 to 45 atomic percentage (%) of copper (Cu), based on the total weight of
the iron-copper alloy. The content unit used in the present invention, i.e., "atomic
percentage (at. %)", is based on the total weight of iron (Fe) and copper (Cu) atoms
(sum of atomic weights of Fe and Cu), which can also be expressed in "volumetric percentage
(vol. %)", as well known in the art. That is to say, in the present invention, at.
% can also be expressed in vol. %.
[0020] In a preferred embodiment, metallic elements other than Fe and Cu are not contained
in the iron-copper alloy according to the present invention. In addition, impurities,
such as carbon (C) or oxygen (O), may be inevitably contained in the iron-copper alloy
according to the present invention, but these impurities are contained in trace amounts.
The impurities may be inevitably contained in an amount of, for example, not greater
than 0.1 at. % (or vol. %), or not greater than 0.01 at. % (or vol. %).
[0021] The iron-copper alloy according to the present invention is an iron based alloy having
copper contained in an appropriate amount and has improved properties owing to well
coordination of the respective merits and advantages of iron and copper. The improved
properties of the iron-copper alloy according to the present invention include at
least high thermal conductivity and mechanical properties. Specifically, the iron-copper
alloy according to the present invention has higher thermal conductivity and elasticity
than existing iron alloys. In addition, the iron-copper alloy according to the present
invention has higher hardness and abrasion resistance than existing copper alloys.
In addition, since low-priced iron is used as a base (main component), the economic
efficiency is high. Moreover, the iron-copper alloy according to the present invention
has an electromagnetic-wave shielding property and soft magnetic property by appropriately
adjusting the composition (content) of iron and copper, so that it can be used in
a wide variety of applications. For example, the iron-copper alloy according to the
present invention can be used for precision parts, such as solenoids, electromagnetic-wave
shielding materials, and materials for 3D printers.
[0022] Hereinafter, a method of manufacturing the iron-copper alloy according to the present
invention will be described with reference to embodiments of the iron-copper alloy
according to the present invention. The manufacturing method that will be described
below can easily implement the manufacture of the iron-copper alloy according to the
present invention. However, the iron-copper alloy according to the present invention
is not to be construed as being limited to the following manufacturing methods.
[0023] The method of manufacturing the iron-copper alloy (to be abbreviated as, "manufacturing
method," hereinafter) according to the present invention includes a first step of
preparing a melting furnace, a second step of adding iron and copper to the melting
furnace and performing dissolution and molten metal formation, a third step of stabilizing
the molten metal, and a fourth step of pouring the stabilized molten metal into a
casting mold and performing casting. Optionally, the manufacturing method according
to the present invention may further include a fifth step of obtaining an iron-copper
alloy existing in powdered particles from the casting obtained in the fourth step.
An embodiment of the manufacturing method according to the present invention will
now be described with respect to various processing steps.
(1) Preparation of melting furnace (First step)
[0024] As described above, the iron-copper alloy according to the present invention contains
55 to 95 at. % of iron (Fe) and 5 to 45 at. % of copper (Cu). The alloy composition
specified in the present invention is not a theoretical molten alloy composition.
That is to say, the alloy composition specified in the present invention is a proportion
in which the Fe content exceeds a theoretical amount of iron (Fe) alloyed. Such an
alloy composition can be implemented in a case of manufacturing a master alloy using
sintering. However, it is difficult to achieve amorphous, complete alloy formation
by melting through dissolution (molten metal formation). In general, iron and copper
can be melted and alloyed when the Fe content is smaller than the Cu content (for
example, the Fe content being less than 2.5 vol. %). In the alloy composition specified
in the present invention, however, separation of two phases, i.e., a Fe-rich phase
and a Cu-rich phase, may occur to the molten metal, resulting in segregation (one
of the two metals being biased to one place), which makes it difficult to achieve
uniformly-distributed, complete molten alloy formation.
[0025] The present inventor repeatedly conducted intensive and thorough research on methods
for forming a complete molten alloy having a high Fe content, resulted in the finding
that the complete molten alloy without segregation (being biased) can be formed when
impurity content is minimized with the Cu content titrated, and/or when a dissolution
process is modified. In the present invention, complete molten alloy formation can
be achieved by improving a melting furnace and/or by improving a raw material adding
method during dissolution according to a specific embodiment.
[0026] In the first step, one embodiment for solving the objective of the present invention
is provided. In the first step, the melting furnace for forming the iron-copper molten
metal is prepared. Here, a high-frequency inductively heated melting furnace, which
enables fast dissolution by being rapidly heated, may be used as the melting furnace.
In addition, the melting furnace is preferably a ceramic melting furnace including
magnesium as a main component. For example, a melting furnace manufactured by performing
high-temperature firing on a ceramic material containing, for example, magnesium oxide
as a main component, may be used as the ceramic melting furnace.
[0027] In a preferred embodiment, the melting furnace is used in such a manner that a porous
impurity absorption layer is formed on its inner surface. In detail, the first step
includes preparing a high-frequency inductively heated ceramic melting furnace and
performing surface treatment for forming a porous impurity absorption layer on the
inner surface of the ceramic melting furnace. Here, the impurity absorption layer
is entirely or partially formed on the inner surface of the melting furnace, specifically
on at least internal bottom surface and/or an internal wall surface of the melting
furnace, which is a surface being in contact with the molten metal.
[0028] In addition, the impurity absorption layer includes at least an impurity absorbent.
In detail, in the step of performing surface treatment, an absorption layer composition
including the impurity absorbent, a resin and a solvent, is coated on the inner surface
of the melting furnace, followed by firing, thereby forming the porous impurity absorption
layer. According to the present invention, impurities contained in the iron-copper
molten metal (e.g., C, O, etc.) can be absorbed by the porous impurity absorption
layer for removal, thereby attaining a complete alloy without segregation (being biased)
even with the non-theoretical alloy composition. The porous impurity absorption layer
may have a thickness, for example, in the range from 0.5mm to 2 mm, but aspects of
the present invention are not limited thereto.
[0029] The impurity absorbent is not particularly limited as long as it can absorb and remove
impurities contained in the iron-copper molten metal (e.g., C, O, etc.). The impurity
absorbent is in the form of powders having a particle size in the range from, for
example, 50 µm to 500 µm. The impurity absorbent may be selected from a metal oxide
and/or a metal. The impurity absorbent preferably includes at least one selected from
zirconium silicate and aluminum (Al). More preferably, zirconium silicate and aluminum
(Al) can be both used as the impurity absorbent. Here, the aluminum (Al) may have
high purity of at least 99.8% by weight (to be abbreviated as wt. %). In the present
invention, the zirconium silicate and aluminum (Al) are preferably used as impurity
absorbents because they are more effective than other metal oxides or metals in completely
removing the impurities contained in the molten metal. In detail, the zirconium silicate
and aluminum (Al) can completely remove impurities contained in the molten metal,
thereby forming high-purity molten metal alloy containing only iron and copper, which
can be confirmed by the following examples.
[0030] In addition, the resin is not particularly limited as long as it has adhesiveness.
The resin, which offers initial adhesion between the inner surface of the melting
furnace and the impurity absorption layer while providing cohesion between powder
particles of the impurity absorbent, is preferably used. In addition, the resin is
removed by high-temperature heat derived from firing, thereby imparting porosity to
the impurity absorption layer. The resin may be selected from a synthetic resin and/or
a natural resin. The resin may exist in a solid phase and/or a liquid phase. Examples
of the resin may include at least one polymer and/or copolymers thereof, which are
selected from the group consisting of an acryl-based resin, a vinyl-based resin, an
epoxy-based resin, an urethane-based resin, a silicone-based resin, an olefin-based
resin, an ester-based resin, a rubber-based resin, and so on.
[0031] A butadiene-styrene-alkyl methacrylate copolymer is preferably used as the resin.
Specific examples of the butadiene-styrene-alkyl methacrylate copolymer may be selected
from the group consisting of a butadiene-styrene-methyl methacrylate copolymer, a
butadiene-styrene-ethyl methacrylate copolymer and/or a butadiene-styrene-butyl methacrylate
copolymer. In an exemplary embodiment, the butadiene-styrene-alkyl methacrylate copolymer
useful in the present invention may have a particle size in the range from 50 nm to
500 nm. When a butadiene-styrene-alkyl methacrylate copolymer is selected as the resin
and is nano-sized, it can be rapidly removed through firing and can be evenly distributed
in the powdered impurity absorbent. Accordingly, the adhesion of the impurity absorbent
can be improved, and a uniform microporous structure is formed in the impurity absorption
layer, thereby improving impurity absorbing/removing capability.
[0032] The solvent, which is associated with dispersibility and coating performance, may
be selected from hydrocarbon-based solvents. Examples of the solvent may be selected
from alcohols and/or ketones.
[0033] In addition, in an exemplary embodiment, the absorption layer composition may include
50 wt. % to 80 wt. % of an impurity absorbent, 5 wt. % to 20 wt. % of a resin, and
15 wt. % to 40 wt. % of a solvent. Here, when the content of the impurity absorbent
is less than 50 wt. %, the impurity absorbing/removing capability may be negligible,
and when the content of the impurity absorbent is greater than 80 wt. %, the porosity
and coating performance may be degraded. In addition, when the content of the resin
is less than 5 wt. %, the porosity and coating performance may be degraded, and when
the content of the resin is greater than 20 wt. %, the content of the impurity absorbent
is relatively reduced, so that the impurity absorbing/removing capability may become
negligible. In addition, in consideration of dispersibility and coating performance,
the content of the solvent is preferably in the range stated above.
[0034] As described above, in a case where the porous impurity absorption layer is formed
on the inner surface of the melting furnace in the first step, the impurities contained
in the molten metal can be absorbed and removed during dissolution, thereby enabling
homogenized, complete iron-copper alloy formation and effectively obtaining a high-purity
iron-copper alloy containing little impurities.
(2) Performing dissolution (Second step)
[0035] Alloying materials, i.e., iron and copper, are added to the melting furnace. Here,
high-purity iron and high-purity electrolytic copper may be used as the alloying materials.
The temperature of the melting furnace may be raised by high-frequency inductively
heating by applying power to the melting furnace. The melting furnace is preferably
maintained in a temperature range in which iron and copper can be dissolved. For example,
the melting furnace is preferably maintained at a temperature in the range from approximately
1,520°C to approximately 1,650°C by being rapidly heated using the high-frequency
inductively heating. During the dissolution, stirring may be performed.
[0036] In addition, in the second step, iron and copper are added to the melting furnace
to then perform dissolution to form a molten metal so as to contain 55 to 95 at. %
of iron and 5 to 45 at. % of copper, based on the total weight of the finally produced
iron-copper alloy. In detail, when the amounts of iron and copper added to the melting
furnace are 55 to 95 vol. % and 5 to 45 vol. % in total (i.e., Fe:Cu = 55 to 95:5
to 45 in a volume ratio), the alloy composition may be obtained. Here, when the content
of copper is less than 5 at. % (or vol. %), improving effects of various properties
including, for example, thermal conductivity, corrosion resistance and/or electromagnetic-wave
shielding property, may be insignificant. In addition, when the content of copper
is greater than 45 at. % (or vol. %), the content of iron is relatively reduced, so
that mechanical properties including, for example, hardness and/or abrasion resistance
may be degraded.
[0037] In light of the foregoing, in a preferred embodiment of the present invention, in
consideration of the foregoing, iron and copper are preferably added to the melting
furnace to then perform dissolution to form a molten metal in the second step so as
to contain 80.5 to 95 at. % of iron and 5 to 19.5 at. % of copper, based on the total
weight of the final product, that is, the iron-copper alloy. That is to say, when
the amounts of iron and copper added to the melting furnace are 80.5 to 95 vol. %
and 5 to 19.5 vol. % in total (i.e., Fe:Cu = 80.5 to 95:5 to 19.5 in a volume ratio),
the alloy composition may be obtained. In this case, the alloy composition may have
excellent thermal conductivity, mechanical properties, electromagnetic-wave shielding
property and/or soft magnetic property.
[0038] In an embodiment, when iron and copper are added to the melting furnace, iron and
copper may be initially added in a volume ratio of 1:1 to then be rapidly dissolved
while stirring, followed by additionally adding iron to the melting furnace to have
the alloy composition. That is to say, it is desirable to obtain a uniformly-distributed
iron-copper alloy by adding iron and copper in the volume ratio of 1:1 at an initial
stage and additionally adding iron at a later stage, rather than by adding iron and
copper at a time. In addition, when iron is additionally added, it is desirable to
intermittently add iron little by little. That is to say, in order to obtain a uniformly-distributed
iron-copper molten alloy, it is advantageous to additionally add small amounts of
iron over several times.
[0039] In addition, the second step (dissolution) may be performed while deoxidizing (preventing
oxidation) by adding a deoxidizer to the melting furnace in a conventional manner.
In addition, a flux may further be added in the second step (dissolution), like in
a conventional method. Here, as the deoxidizer and the flux, any deoxidizer and any
flux generally used in the related art may be used. For example, at least 99.8 wt.
% of high-purity Al and/or high-purity Ti, may be used as the deoxidizer, and Al
2O
3, CaO and/or SiO
2 may be used as the flux.
(3) Stabilizing (Third step)
[0040] The molten metal resulting from the dissolution is stabilized. The stabilization
may be performed such that the molten metal is left undisturbed in the melting furnace
for a predetermined time while shutting off the power supply. For example, the stabilization
may be performed by maintaining the molten metal at a temperature in the range from
1,450°C to 1,520°C and leaving the molten metal undisturbed. As the result of the
stabilization, homogenization of iron and copper may be achieved.
(4) Casting (Fourth step)
[0041] The stabilized molten metal is poured into a casting mold to cast the same into an
alloy casting having a predetermined shape. The fourth step (casting) is performed
in accordance with a general process. The casting mold is not particularly limited
in shape, and may be shaped of an ingot or a cast piece. In some cases, the casting
mold may be shaped of a ready-to-use product. In addition, the casting mold may have
a cooling function, like a conventional casting mold.
[0042] In addition, the casting obtained in the fourth step may be subjected to post treatment
through a general post treatment process, such as heat treatment and/or cooling. Specifically,
the casting may be post-treated by, for example, annealing, normalizing, quenching
and/or tempering. The post treatment may be appropriately selected according to the
use and product to be applied. For example, in a case of a product requiring a mechanical
strength (tensile strength, hardness, etc.), quenching and tempering may be performed.
In addition, the casting may have a variety of shapes through remelting and/or post-processing,
and may be processed into a ready-to-use product or a half-finished product.
(5) Granulating (Fifth step)
[0043] The fifth step is an optional process, which is performed to obtain powdered iron-copper
alloy particles. In the fifth step, the casting obtained in the fourth step (casting)
is remelted and injected, thereby obtaining the powdered iron-copper alloy particles.
In detail, the fifth step may include remelting the casting, injecting the remelted
casting and granulating the same to obtain the powdered iron-copper alloy particles.
[0044] Here, the same melting furnace as used in the first step may be used in the remelting
step. In addition, in order to prevent the iron-copper alloy from being oxidized in
the remelting of the fifth step, the remelting is preferably performed in a vacuum
melting furnace. That is to say, a vacuum furnace may be used as the melting furnace.
The casting may be remelted in the vacuum furnace at a temperature in the range from
1,600°C to 1,700°C. In the granulating step, the remelted casting can be made into
powdered particles by injecting the remelted casting at a temperature in the range
from 1,400°C to 1,500°C. Here, the powdered particles may have a particle size, for
example, in the range from 0.1 µm to 150 µm. The obtained powdered iron-copper alloy
particles are preferably spherical particles.
[0045] According to the above-described manufacturing method, complete alloy formation can
be achieved without segregation (being biased) even with a non-theoretical alloy composition
containing 55 to 95 at. % of iron (Fe) and 5 to 45 at. % of copper (Cu). In addition,
the respective merits and advantages of iron and copper are well coordinated in the
iron-copper alloy manufactured according to the present invention, so that the iron-copper
alloy may have high thermal conductivity and mechanical properties, such as tensile
strength, hardness, abrasion resistance, or the like, along with, for example, an
electromagnetic-wave shielding property and a soft magnetic property, as described
above. Therefore, the iron-copper alloy can be widely used for a variety of purposes.
[0046] In a preferred embodiment, the iron-copper alloy according to the present invention
may contain 80.5 to 95 at. % (or vol. %) of iron and 5 to 19.5 at. % (or vol. %) of
copper. More specifically, the iron-copper alloy according to the present invention
may contain 82.5 to 90.5 at. % (or vol. %) of iron and 9.5 to 17.5 at. % (or vol.
%) of copper. In this case, properties of the iron-copper alloy, including thermal
conductivity, mechanical properties, electromagnetic-wave shielding property and/or
soft magnetic property, may be effectively improved.
[0047] In addition, the iron-copper alloy according to the present invention may have the
following properties (a) to (c). When the iron-copper alloy according to the present
invention has the following properties (a) to (c), the iron-copper alloy can be generally
used not only as a molding material for injection molding or die casting but also
as a material for a 3D printer:
- (a) thermal conductivity of 70 W/m · K or higher;
- (b) tensile strength of 300 N/mm2 or greater; and
- (c) hardness of 100 HB or greater.
[0048] The thermal conductivity, tensile strength and hardness may be determined in accordance
with a general measuring method. The thermal conductivity may be a value measured
at room temperature (20°C to 25°C) in conformity with the ASTM E1461 standard (Laser
flash: Thru-Plane thermal conductivity). In addition, the tensile strength may be
measured in conformity with the KS B 0801 standard and the hardness may be measured
in conformity with the KS B 0805 standard.
[0049] Specifically, the iron-copper alloy may have a thermal conductivity in the range
from 70 to 150 W/m · K, for example. In addition, the iron-copper alloy may have a
tensile strength, for example, in the range from 300 to 1,350 N/mm
2. In addition, the iron-copper alloy may have a hardness, which is a Brinell hardness,
in the range from 100 HB to 400 HB. The respective properties of the iron-copper alloy
may be optimized according to the use in applied fields. For example, the tensile
strength and hardness can be increased by the aforementioned post treatment (e.g.,
normalizing, quenching, tempering, and so on). After the post treatment, the iron-copper
alloy may have a tensile strength of 500 N/mm
2 or greater and a hardness of 200 HB or greater.
[0050] In an exemplary embodiment, along with the properties (a) to (c), the iron-copper
alloy according to the present invention may have (d) magnetic permeability of 45
to 650 m
m. The magnetic permeability may be determined in accordance with a general measuring
method for a magnetic material (e.g., metals, etc.), and may be a value measured at
a low frequency of 50 Hz. In addition, the iron-copper alloy according to the present
invention preferably is in a spherical particle shape. The spherical particle shape
can be implemented through the fifth step. Here, the iron-copper alloy according to
the present invention has a spherical particle shape and may have a particle size
in the range, for example, from 0.1 µm to 150 µm. As described above, when the iron-copper
alloy is in the spherical particle shape, it can be useful as a material for 3D printer.
In the present invention, the term "spherical" used is not to be construed as being
perfectly spherical but is to be construed as being "quasi-spherical" as well as "perfectly
spherical".
[0051] In the present invention, "spherical particles" suggest that iron and copper are
uniformly distributed in the alloy without segregation (being biased) and complete
molten alloy formation is achieved even if the iron-copper alloy has a non-theoretical
alloy composition. In this respect, the spherical particles are technically significant.
That is to say, when complete molten alloy formation is not achieved, spherical particles
can be hardly obtained through injecting process. In the present invention, the spherical
particles may also have technical significance in that an iron-copper alloy molded
article having a uniform composition through remelting can be manufactured.
[0052] Meanwhile, the iron-copper alloy according to the present invention can be widely
employed for a variety of application fields and uses, and the application fields
and uses are not particularly limited. As described above, the iron-copper alloy according
to the present invention may be used not only as a molding material but also as electronic
parts, high-temperature machine parts, precision machine parts, materials for 3D printers,
and so on. In addition, the iron-copper alloy according to the present invention can
be widely employed in various fields, including electric materials, electromagnetic-wave
shielding materials, anti-microbial materials, sensor materials, medical tools for
surgery, energy related fields, coating fields, and so on.
[0053] Hereinafter, Examples of the present invention and Comparative Examples will be described.
The following Examples are provided only by way of example for a better understanding
of the present invention, but the present invention is not limited by those examples.
In addition, the following Comparative Examples do not represent prior art but are
provided only for comparison with Examples of the present invention.
Example 1
<Melting Furnace>
[0054] A ceramic melting furnace containing magnesium as a main component was prepared as
a high-frequency inductively heated melting furnace. Thereafter, a porous impurity
absorption layer was formed on an inner wall surface and a bottom surface of the prepared
melting furnace. The porous impurity absorption layer was formed by coating an absorption
layer composition to a thickness of approximately 1 mm, the composition prepared by
mixing 65 wt. % of an impurity absorbent, 15 wt. % of a resin, and 30 wt. % of a solvent,
based on the total weight of the composition, and then heating at a temperature of
approximately 1,150°C for firing. Here, zirconium silicate (ZrSiO
4) and Al powder were used as the impurity absorbent, a butadiene-styrene-alkyl methacrylate
copolymer was used as the resin, and isopropyl alcohol was used as the solvent.
<Molten metal/Stabilization/Casting>
[0055] Iron (pure iron having purity of approximately 99.9 wt. %) and electrolytic copper
having purity of approximately 99.9 wt. %) were added to the melting furnace in a
volume ratio of 1:1 at an initial stage, and rapid dissolution was performed by increasing
output power while stirring. Here, the dissolution was performed while deoxidizing
(preventing oxidation) by intermittently adding a deoxidizer (Al) to the melting furnace.
In addition, it was confirmed through observation with naked eye whether Fe and Cu
added to the melting furnace were completely dissolved, Fe was additionally added
to the melting furnace little by little to increase the Fe content, and Fe and Cu
were completely dissolved at a temperature of approximately 1,550°C. Thereafter, stabilization
was performed such that the molten metal was left undisturbed in the melting furnace
until the temperature of the melting furnace was raised up to approximately 1,500°C
while shutting off the power supply. Next, the stabilized molten metal was poured
into a casting mold, followed by cooling, thereby obtaining an iron-copper alloy ingot.
Examples 2 and 3
[0056] Iron-copper alloy ingots were prepared in substantially the same manner as in Example
1, except that amounts of iron additionally added during dissolution were changed
for the purpose of making final alloy compositions (atomic percentages of iron and
copper) differ from the alloy composition of Example 1.
Comparative Example 1
[0057] An iron-copper alloy ingot was prepared in substantially the same manner as in Example
1, except that a different kind of impurity absorbent was used in forming a porous
impurity absorption layer on the inner surface of the melting furnace. In detail,
zirconium silicate (ZrSiO
4) and zirconium oxide (ZrO
2), instead of aluminum (Al), were used as the impurity absorbent.
Comparative Example 2
[0058] Unlike in Example 1, iron and copper were added to a melting furnace in a volume
ratio of 9:1 at a time, and an iron-copper alloy used in Comparative Example 2 was
prepared by performing dissolution without forming a porous impurity absorption layer
on an inner surface of the melting furnace.
[0059] Elemental analyses were carried out on the obtained iron-copper alloy samples in
the following manner, and the results are shown in Table 1. In addition, thermal conductivity,
tensile strength, hardness and magnetic permeability of each alloy sample were evaluated,
and the results are also shown in Table 1. The thermal conductivity was measured by
measuring a density, specific heat and thermal diffusivity of each alloy sample, which
is a thermal conductivity measuring method of a metal sample, and then evaluated in
conformity with the ASTM E1461 standard (Laser flash: Thru-plane thermal conductivity).
Here, all tests were carried out at a temperature of 25°C. In addition, the tensile
strength was evaluated in conformity with the KS B 0801 standard, and the hardness
(Brinell hardness) was evaluated in conformity with the KS B 0805 standard. The magnetic
permeability was evaluated at a frequency of 50 Hz using a magnetic permeability tester
(BHU-60 model manufactured by Riken Denshi Co., Ltd., Japan).
<Elemental analysis>
[0060] Weighed alloy samples were placed in a glass beaker and 10 mL of an aqua regia (an
aqueous solution of hydrochloric acid and sulfuric acid) was added thereto for dissolution.
Then, elemental analysis was conducted such that iron and copper were quantified and
their concentrations contained in the respective samples were determined through inductively
coupled plasma-atomic emission spectroscopy (ICP-AES) under the following measurement
conditions.
* Measurement conditions of ICP-AES
- Measuring device: PerkinElmer Optima 5300 DV
- Measurement wavelength: 238.204 nm (Fe), 327.393 nm (Cu)
- Quantitative method: Internal standard method
Table 1: Elemental analysis and property evaluation of Fe-Cu alloys
|
Impurity absorbent |
Composition (at. %) |
Thermal conductivity [W/m · K] |
Tensile strength [N/mm2] |
Brinell hardness [HB] |
Magnetic permeability [mm] |
Fe |
Cu |
Thermal conductivity [W/m · K] |
Tensile strength [N/mm2] |
Brinell hardness [HB] |
Magnetic permeability [mm] |
Exam. 1 |
ZrSiO4 + Al |
89.58 |
10.42 |
74.3 |
327 |
154 |
630 |
Exam. 2 |
ZrSiO4 + Al |
88.32 |
11.68 |
76.6 |
323 |
143 |
613 |
Exam. 3 |
ZrSiO4 + Al |
90.07 |
9.93 |
70.5 |
342 |
161 |
637 |
Comp. Exam. 1 |
ZrO2 |
Segregation |
56.1 |
Cracks |
- |
- |
Comp. Exam. 2 |
- |
Segregation |
47.3 |
Cracks |
- |
- |
[0061] As shown in Table 1, it was confirmed that the iron-copper alloys prepared in Examples
had higher thermal conductivity (70 W/m · K or higher) than those prepared in Comparative
Examples. In addition, each of the iron-copper alloys prepared in Examples had a tensile
strength of 300 N/mm
2 or greater and hardness of 140 HB or greater. Here, the high tensile strength of
320 N/mm
2 or greater means that a uniformly-distributed, complete iron-copper alloy was formed
without segregation (being biased). In addition, the iron-copper alloys prepared in
Examples demonstrated magnetic permeability of approximately 600 m
m, suggesting that they had electromagnetic-wave shielding capability. FIG. 1 shows
a B-H curve (magnetization curve) of an iron-copper alloy prepared in Example of the
present invention, suggesting that the iron-copper alloy prepared in Example 1 had
a soft magnetic property.
[0062] However, in Comparative Examples, complete alloy formation was not achieved and segregation
occurred to the alloys. In addition, cracks were generated due to segregation, making
it impossible to measure the tensile strength of each of the alloys prepared in Comparative
Examples. In addition, since elements of the respective alloys prepared in Comparative
Examples were not uniformly distributed due to segregation, accurate elemental analyses
were not made and the results thereof are not given in Table 1. For the same reason,
the hardness and magnetic permeability of the alloy samples in Comparative Examples
are not given in Table 1, either.
[0063] Table 2 shows property evaluation results according to post treatment, the evaluation
results shown before and after treatment performed specifically on the same alloy
sample with the sample prepared in Example 2. The post treatment was conducted in
a general manner by performing annealing, normalizing, quenching and tempering.
Table 2: Property changes depending on post treatment of iron-copper alloys
|
Before treatment (Exam. 2) |
After treatment |
Annealing |
Normalizing |
Quenching (900°C) + tempering |
Quenching (1,050°C) + tempering |
Tensile strength [N/mm2] |
323 |
301 |
604 |
1,016 |
1,311 |
Elongation [%] |
10 |
30 |
15 |
3 |
1 |
Brinell hardness [HB] |
143 |
100 |
207 |
282 |
374 |
[0064] As shown in Table 2, it was confirmed that the iron-copper alloy experienced property
changes after post treatment. For example, when the post treatment of quenching (and
tempering) was performed at a temperature of 1,050°C, the iron-copper alloy had a
tensile strength of 1,300 N/mm
2 or greater and a hardness of 370 HB or greater, suggesting that the mechanical strength
of the iron-copper alloy was improved, compared to a case where the post treatment
was not performed. As described above, the iron-copper alloy demonstrated improved
mechanical strengths through heat treatment, like a general pure single metal (e.g.,
pure iron, etc.), suggesting that complete alloy formation was achieved by performing
the post treatment on the iron-copper alloy.
Examples 4-6
[0065] Iron-copper alloy ingots were prepared in substantially the same manner as in Example
1, except that amounts of iron additionally added during dissolution were changed
for the purpose of making final alloy compositions (atomic percentages of iron and
copper) differ from the alloy composition of Example 1. In addition, in Examples 4-6,
the iron-copper alloy ingots obtained through casting were granulated in the following
manner to prepare powdered iron-copper alloy particles.
[0066] First, iron-copper alloy ingots according to Examples 4-6, which were obtained through
casting, were placed in a high-frequency inductively heated melting furnace, and maximum
power was applied thereto to perform remelting at a temperature of approximately 1,650°C.
Here, the melting furnace was maintained in a vacuum state to prevent oxidation. Next,
the remelted casting was granulated by injecting the same into an injection chamber
using an injector. Here, the injection chamber was maintained in an argon (Ar) gas
atmosphere to prevent oxidation, and the remelted casting was injected at a temperature
of 1,450°C, thereby manufacturing the powdered iron-copper alloy particles.
[0067] FIGS. 2 to 5 show scanning electron micrograph (SEM) photographs of powdered iron-copper
alloy particles prepared in Examples 4 to 6 of the present invention. Specifically,
FIG. 2 shows scanning electron micrograph (SEM) photographs of iron-copper alloy particles
prepared in Example 4 of the present invention according to magnification scales,
and FIG. 3 shows an EDS analysis result of iron-copper alloy particles prepared in
Example 4 of the present invention. In addition, FIG. 4 shows an EDS analysis result
of iron-copper alloy particles prepared in Example 5 of the present invention, and
FIG. 5 shows an EDS analysis result of iron-copper alloy particles prepared in Example
6 of the present invention.
[0068] As shown in FIG. 2 to 5, the iron-copper alloy particles manufactured according to
Examples 4-6 are fine particles of a particle size of 30 µm or less, which have an
almost perfectly spherical shape. As shown from three photographs in the lower part
of FIG. 3 showing distributions of iron and copper (iron: red; copper: green), iron
and copper are uniformly distributed without segregation (being biased). Among the
three photographs in the lower part of FIG. 3, the middle photograph shows a distribution
of iron (red), the right photograph shows a distribution of copper (green), and the
left photograph shows a distribution of iron and copper. In this way, the iron-copper
alloy particles having perfectly spherical shapes and showing a uniform distribution
suggest that iron and copper were completely alloyed.
[0069] FIG. 6 shows an SEM photograph of a particle sample using an ingot prepared in Comparative
Example 2. As shown in FIG. 6, in Comparative Example 2, the particles had shapes
of amorphous pieces due to segregation, suggest that iron and copper were not completely
alloyed.